[Explosives-based vole traps-A novel injury pattern in the eye region]. / Sprengstoffbasierte Wühlmausfallen ­ ein neuartiges Verletzungsmuster im Augenbereich.

BACKGROUND: A novel method for trapping voles is the use of pistol-like explosive tools loaded with bolt-action ammunition. When triggered the vole is killed by the very high gas pressure created. Accidental releases can result in facial and/or eye injuries. The aim of this work was to describe the injury pattern in the patient and to experimentally verify whether there is a risk of penetrating eye injuries. METHODS: Two emergency patients presented to our eye clinic with eye injuries after unintentional triggering of the explosive trap. Based on the new pattern of injury noted, experiments were performed on enucleated porcine eyes to determine the possible severity. For this purpose, a vole trap was clamped in a holder and loaded with a Cal. 9â€¯× 17 mm cartridge in each case. In front of the muzzle opening, 3 pig eyes each were fixed on Styrofoam at a distance of 20, 40, 60 and 80 cm. The foreign body indentations in the cornea were visualized and measured by spectral domain optical coherence tomography (SD-OCT). The pig eyes were then dissected and searched for foreign bodies using microscopy. The SD-OCT images of an injured patient were also included for human comparison. RESULTS: On patient examination, in addition to the usual fine gunshot marks on the face and conjunctiva/eye area, wax-like, larger and heavier particles of approximately 0.1-0.2 mm in size were found, which originated from the cartridge end cap. Removal of these foreign bodies, some of which were injected more deeply into the cornea, conjunctiva, and tenon, is much more difficult and extensive than in usual blast trauma. There was no evidence of intraocular foreign bodies in either patient. Likewise, no intraocular foreign bodies could be detected experimentally in any pig eyeball (n = 12). Remnants of the wax-like cartridge end were found deeply penetrating into the corneal stroma. The maximum penetration depth measured against the total corneal thickness was 46% at 20 cm device distance and decreased with greater distance to the vole trap (penetration depth at 40 cm at 37%, at 60 cm at 28% and at 80 cm at 19%). For comparisons on the human eye, a penetration depth of 54% was measured at a distance of about 40 cm. In pig eyes the number of foreign bodies per cm2 decreased with increasing distance from the vole trap (mean: n = 174 foreign bodies, FB, at 20 cm distance, n = 46 FB at 40 cm, n = 23 FB at 60 cm, and n = 9 FB at 80 cm). The largest penetrating foreign bodies measured a mean of 383 ± 43 µm with a maximum of 451 µm. CONCLUSION: New vole traps with gas-powered mechanisms result in larger deeply penetrating wax-like foreign bodies in the cornea, conjunctiva, and tenon of the eye, which are difficult to remove and only surgically possible. Despite the significant explosion during triggering, there was no evidence of penetrating ocular injury from the foreign bodies either in the patient or experimentally in the pig eyes. Safety goggles should be worn when handling the traps to avoid penetration of foreign bodies into the eye.

Long-term type 1 diabetes influences haematopoietic stem cells by reducing vascular repair potential and increasing inflammatory monocyte generation in a murine model.

AIMS/HYPOTHESIS: We sought to determine the impact of long-standing type 1 diabetes on haematopoietic stem/progenitor cell (HSC) number and function and to examine the impact of modulating glycoprotein (GP)130 receptor in these cells. METHODS: Wild-type, gp130(-/-) and GFP chimeric mice were treated with streptozotocin to induce type 1 diabetes. Bone marrow (BM)-derived cells were used for colony-formation assay, quantification of side population (SP) cells, examination of gene expression, nitric oxide measurement and migration studies. Endothelial progenitor cells (EPCs), a population of vascular precursors derived from HSCs, were compared in diabetic and control mice. Cytokines were measured in BM supernatant fractions by ELISA and protein array. Flow cytometry was performed on enzymatically dissociated retina from gfp(+) chimeric mice and used to assess BM cell recruitment to the retina, kidney and blood. RESULTS: BM cells from the 12-month-diabetic mice showed reduced colony-forming ability, depletion of SP-HSCs with a proportional increase in SP-HSCs residing in hypoxic regions of BM, decreased EPC numbers, and reduced eNos (also known as Nos3) but increased iNos (also known as Nos2) and oxidative stress-related genes. BM supernatant fraction showed increased cytokines, GP130 ligands and monocyte/macrophage stimulating factor. Retina, kidney and peripheral blood showed increased numbers of CD11b(+)/CD45(hi)/ CCR2(+)/Ly6C(hi) inflammatory monocytes. Diabetic gp130(-/-) mice were protected from development of diabetes-induced changes in their HSCs. CONCLUSIONS/INTERPRETATION: The BM microenvironment of type 1 diabetic mice can lead to changes in haematopoiesis, with generation of more monocytes and fewer EPCs contributing to development of microvascular complications. Inhibition of GP130 activation may serve as a therapeutic strategy to improve the key aspects of this dysfunction.

Examples of model-free implant restorations using Cerec inLab 4.0 software.

This case report demonstrates two ways to fabricate model-free implant restorations with the Cerec inLab 4.0 software. Because the patient, a woman with a history of periodontal disease, did not wish to have a removable partial denture, implant therapy was planned for the restoration of her edentulous areas 14/15 and 24/25. In addition, the restoration was to provide functional relief of the natural maxillary anterior teeth. The two implants for the first quadrant were planned as single-tooth restorations. Each was designed as a full contour implant supra-structure using the Cerec Biogeneric abutment design technique. After completing the design phase, each restoration proposal was split into two parts: a zirconia abutment and a lithium disilicate crown. For the restoration of the second quadrant, custom 20-degree-angled abutments were individualized and acquired with the Cerec camera. A block crown was then designed, milled in burn-out acrylic resin, and fabricated from a lithium disilicate glass-ceramic ingot according to the press ceramic technique. Additionally methods of provisional restorations are discussed.

Backbone and side-chain 1H, 15N and 13C assignment of apo- and imipenem-acylated L,D-transpeptidase from Bacillus subtilis.

The D,D-transpeptidase activity of Penicillin Binding Proteins (PBPs) is essential to maintain cell wall integrity. PBPs catalyze the final step of the peptidoglycan synthesis by forming 4 → 3 cross-links between two peptide stems. Recently, a novel ß-lactam resistance mechanism involving L,D-transpeptidases has been identified in Enterococcus faecium and Mycobacterium tuberculosis. In this resistance pathway, the classical 4 → 3 cross-links are replaced by 3 → 3 cross-links, whose formation are catalyzed by the L,D-transpeptidases. To date, only one class of the entire ß-lactam family, the carbapenems, is able to inhibit the L,D-transpeptidase activity. Nevertheless, the specificity of this inactivation is still not understood. Hence, the study of this new transpeptidase family is of considerable interest in order to understand the mechanism of the L,D-transpeptidases inhibition by carbapenems. In this context, we present herein the backbone and side-chain (1)H, (15)N and (13)C NMR assignment of the L,D-transpeptidase from Bacillus subtilis (Ldt(Bs)) in the apo and in the acylated form with a carbapenem, the imipenem.

Omega-3 polyunsaturated fatty acids preserve retinal function in type 2 diabetic mice.

OBJECTIVE: Diabetic retinopathy (DR) is associated with hyperglycemia-driven microvascular pathology and neuronal compromise in the retina. However, DR is also linked to dyslipidemia. As omega-3 (ω-3) polyunsaturated fatty acids (PUFAs) are protective in proliferative retinopathy, we investigated the capacity of ω-3PUFAs to preserve retinal function in a mouse model of type 2 diabetes mellitus (T2DM). DESIGN: Male leptin-receptor-deficient (db/db) mice were maintained for 22 weeks (4 weeks-26 weeks of life) on calorically and compositionally matched diets, except for 2% enrichment in either ω-3 or ω-6PUFAs. Visual function was assessed at 9, 14 and 26 weeks by electroretinography. Retinal capillary and neuronal integrity, as well as glucose challenge responses, were assessed on each diet. RESULTS: The ω-3PUFA diet significantly preserved retinal function in the mouse model of T2DM to levels similar to those observed in nondiabetic control mice on normal chow. Conversely, retinal function gradually deteriorated in db/db mice on a ω-6PUFA-rich diet. There was also an enhanced ability of ω-3PUFA-fed mice to respond to glucose challenge. The protection of visual function appeared to be independent of cytoprotective or anti-inflammatory effects of ω-3PUFAs. CONCLUSION: This study identifies beneficial effects of dietary ω-3PUFAs on visual function in T2DM. The data are consistent with dyslipidemia negatively impacting retinal function. As ω-3PUFA lipid dietary interventions are readily available, safe and inexpensive, increasing ω-3PUFA intake in diabetic patients may slow the progression of vision loss in T2DM.

[Healthcare system and aspects of healthcare economics: sector ophthalmology--part 3: inpatient treatment]. / Gesundheitssystem und gesundheitsökonomische Aspekte: Bereich Augenheilkunde--Teil 3: Stationäre Versorgung.

With annual costs of nearly 60 billion EUR, hospitals account for a large portion of the total costs of the German statutory health insurance, which stand at 178 billion EUR. The introduction of diagnosis-related groups (DRGs) was intended to reduce the demands on the healthcare system and promote a more economic approach in the system. This article presents the current DRGs since the discontinuation of care payments and explains how profits can be made applying the DRG system. Important issues such as base rate, cost weight, case mix or case mix index are discussed. The key figures for hospitals in terms of budget calculation are presented. Average inpatient stays were shortened following the introduction of DRGs in Germany. The relevance of surcharges and deductions in the case of non-observance of prescribed patient stays is discussed.

NF-κB subunits are differentially distributed in cells of lumbar dorsal root ganglia in naïve and diabetic rats.

Previous studies demonstrated that nuclear factor κB (NF-κB) activation is decreased in dorsal root ganglia (DRG) of rats having streptozotocin (STZ)-induced diabetes. DRG contain cell bodies of neurons that convey sensory signals from the periphery. To determine the relationship between diabetes-induced neuropathy and NF-κB expression in DRG, behavioral, immunohistochemical, and biochemical studies were performed on naïve and 3-month diabetic rats. Behavioral studies confirmed that many diabetic rats develop tactile allodynia, or increased sensitivity to light touch, in the hind paws. Immunohistochemical studies on lumbar DRG that receive input from the affected regions revealed that p50 and p65, frequent NF-κB subunit partners, are differentially localized. Intense p65 immunostaining was detected in the cytoplasm of small- and medium-sized neurons as well as in satellite cells. In contrast, p50 was localized in the cytoplasm of virtually all neurons. In many cases, prominent staining was also present in nuclei, a location consistent with transcription factor activation. Immunohistochemical and biochemical studies found that the nuclear to cytoplasmic ratio of p50 expression was significantly reduced in diabetic rats compared to that in naïve animals. Our findings raise the possibility that changes in NF-κB activation in a subset of DRG neurons participates in mediating diabetes-induced sensory neuropathy.

Validation of structural and functional lesions of diabetic retinopathy in mice.

Diabetic retinopathy is a serious long-term complication of diabetes mellitus. There is considerable interest in using mouse models, which can be genetically modified, to understand how retinopathy develops and can be inhibited. Not all retinal lesions that develop in diabetic patients have been reproduced in diabetic mice; conversely, not all abnormalities found in diabetic mice have been studied or identified in diabetic patients. Thus, it is important to recognize which structural and functional abnormalities that develop in diabetic mice have been validated against the lesions that characteristically develop in diabetic patients. Those lesions that have been observed to develop in the mouse models to date are predominantly characteristic of the early stages of retinopathy. Identification of new therapeutic ways to inhibit these early lesions is expected to help inhibit progression to more advanced and clinically important stages of retinopathy.

[Healthcare system and aspects of healthcare economics. Sector ophthalmology--Part 2: Outpatient care]. / Gesundheitssystem und gesundheitsökonomische Aspekte. Bereich Augenheilkunde--Teil 2: Ambulante Versorgung.

In part 2 of this work on the German healthcare system with special emphasis on ophthalmology, the outpatient healthcare system is presented. The payment modalities for physicians working in medical practices are explained because this concerns 90% of the population. Special attention is paid to patients who are members of health insurance funds and later on remuneration for private patients and employer's liability insurance associations is dealt with. Because the distinction between the inpatient and outpatient sectors should be reduced, the latest changes introduced by the government are explained.

[Health care systems and aspects of health care economics. Sector ophthalmology - part 1: development of the German health care system]. / Gesundheitssystem und gesundheitsökonomische Aspekte: Bereich Augenheilkunde - Teil 1: Entwicklung des deutschen Gesundheitssystems.

Although many health care reforms have been enacted in the last few years in Germany, many of the key points in the current social health care system have been retained from former times. All those introductions for an effective health care system from the last 150 years beginning with mandatory guild membership via Bismarck's social laws to the modern health care systems in Germany with the current problems of financing the heavy burden in the German budget are reported. Data and facts on the current health care system are provided. In the following two articles of this series ambulatory and inpatient treatment in the light of economic aspects of health care are reported.

PP2A contributes to endothelial death in high glucose: inhibition by benfotiamine.

Endothelial death is critical in diabetic vascular diseases, but regulating factors have been only partially elucidated. Phosphatases play important regulatory roles in cell metabolism, but have not previously been implicated in hyperglycemia-induced cell death. We investigated the role of the phosphatase, type 2A protein phosphatase (PP2A), in hyperglycemia-induced changes in signaling and death in bovine aortic endothelial cells (BAEC). We explored also the influence of benfotiamine on this phosphatase. Activation of PP2A was assessed in BAEC by the extent of methylation and measurement of activity, and the enzyme was inhibited using selective pharmacological (okadaic acid, sodium fostriecin) and molecular (small interfering RNA) approaches. BAECs cultured in 30 mM glucose significantly increased PP2A methylation and activity, and PP2A inhibitors blocked these abnormalities. PP2A activity was increased also in aorta and retina from diabetic rats. NF-κB activity and cell death in BAEC were significantly increased in 30 mM glucose and inhibited by PP2A inhibition. NF-κB played a role in the hyperglycemia-induced death of BAEC, since blocking its translocation with SN50 also inhibited cell death. Inhibition of PP2A blocked the hyperglycemia-induced dephosphorylation of NF-κB and Bad, thus favoring cell survival. Incubation of benfotiamine with BAEC inhibited the high glucose-induced activation of PP2A and NF-κB and cell death, as well as several other metabolic defects, which likewise were inhibited by inhibitors of PP2A. Activation of PP2A contributes to endothelial cell death in high glucose, and beneficial actions of benfotiamine are due, at least in part, to inhibition of PP2A activation.

Comparison of three strains of diabetic rats with respect to the rate at which retinopathy and tactile allodynia develop.

PURPOSE: We compared three rat strains to determine if different strains develop early-stage diabetic retinopathy or sensory neuropathy at different rates. METHODS: Sprague Dawley, Lewis, and Wistar rats were made diabetic with streptozotocin. Diabetic and nondiabetic animals had retinal vascular pathology measured at eight months of diabetes. The number of cells in the retinal ganglion cell layer (GCL), retinal function (using electroretinography [ERG]), and retinal levels of inducible nitric oxide synthase (iNOS), cyclooxygenase2 (COX2), and vascular endothelial growth factor (VEGF) were measured at four months of diabetes. Tactile allodynia was assessed in hind paws at two months of diabetes. RESULTS: Diabetes of eight months' duration resulted in a significant increase in retinal degenerate capillaries and pericyte ghosts in Lewis and Wistar rats, but not in Sprague Dawley rats. A significant loss of cells in the GCL occurred only in diabetic Lewis rats, whereas Wistar and Sprague Dawley rats showed little change. Diabetes-induced iNOS and VEGF were statistically significant in all strains. Cyclooxygenase 2 (COX2) was significantly elevated in the Sprague Dawley and Wistar strains. Lewis rats showed a similar trend, however, the results were not statistically significant. All strains tended to show diabetes-induced impairment of dark-adapted b-wave amplitude, but only Sprague Dawley and Lewis strains had a significant reduction in latency. All strains showed significant tactile allodynia in peripheral nerves. CONCLUSIONS: At the durations studied, Lewis rats showed accelerated loss of both retinal capillaries and ganglion cells in diabetes, whereas diabetic Wistar rats showed degeneration of the capillaries without significant neurodegeneration, and Sprague Dawley rats showed neither lesion. Identification of strains that develop retinal lesions at different rates should be of value in investigating the pathogenesis of retinopathy.

[Complications after refractive surgery abroad]. / Komplikationen nach refraktiver Chirurgie im Ausland.

BACKGROUND: In this article a retrospective analysis of patients presenting at a German university following refractive surgery abroad is presented. PATIENTS AND METHODS: A total of 20 cases of patients who had undergone treatment between 1998 and 2006 in China (1 case), Greece (1 case), Iran (1 case), Russia (2 cases), Switzerland (1 case), Slovakia (1 case), Spain (2 cases), South Africa (3 cases), Turkey (6 cases) and the USA (2 cases) were analyzed retrospectively. RESULTS: The following complications were observed: epithelial ingrowth into the interface with or without melting of the flap (6 cases), corneal ectasia (2 cases), dislocation of a phakic posterior chamber intraocular lens and prolapse into the anterior chamber with endothelial cell loss (1 case), secondary increase of intraocular pressure following implantation of a phakic intraocular lens (1 case), flap-related complications following laser-in-situ keratomileusis (LASIK) (2 cases), keratitis (1 case), dislocation of the complete flap (1 case), diffuse lamellar keratitis (DLK) grade IV (1 case), hyperopia as a consequence of radial keratotomy (1 case), and under correction/over correction and poor optical quality following laser epithelial keratomileusis (LASEK) and LASIK for high myopia (5 cases) with possible early corneal ectasia. CONCLUSIONS: There are four important problems arising from refractive surgery abroad, often referred to as "LASIK tourism": wrong indications, insufficient management of complications, lack of postoperative care and the health economic aspect.

Critical role of inducible nitric oxide synthase in degeneration of retinal capillaries in mice with streptozotocin-induced diabetes.

AIMS/HYPOTHESIS: Diabetes results in the upregulation of the production of several components of the inflammatory response in the retina, including inducible nitric oxide synthase (iNOS). The aim of this study was to investigate the role of iNOS in the pathogenesis of the early stages of diabetic retinopathy using iNOS-deficient mice (iNos (-/-)). MATERIALS AND METHODS: iNos (-/-) mice and wild-type (WT; C57BL/6J) mice were made diabetic with streptozotocin or kept as non-diabetic controls. Mice were killed at different time points after the induction of diabetes for assessment of vascular histopathology, cell loss in the ganglion cell layer (GCL), retinal thickness, and biochemical and physiological abnormalities. RESULTS: The concentrations of nitric oxide, nitration of proteins, poly(ADP-ribose) (PAR)-modified proteins, endothelial nitric oxide synthase, prostaglandin E(2), superoxide and leucostasis were significantly (p < 0.05) increased in retinas of WT mice diabetic for 2 months compared with non-diabetic WT mice. All of these abnormalities except PAR-modified proteins in retinas were inhibited (p < 0.05) in diabetic iNos (-/-) mice. The number of acellular capillaries and pericyte ghosts was significantly increased in retinas from WT mice diabetic for 9 months compared with non-diabetic WT controls, these increases being significantly inhibited in diabetic iNos (-/-) mice (p < 0.05 for all). Retinas from WT diabetic mice were significantly thinner than those from their non-diabetic controls, whereas diabetic iNos (-/-) mice were protected from this abnormality. We found no evidence of cell loss in the GCL of diabetic WT or iNos (-/-) mice. Deletion of iNos had no beneficial effect on diabetes-induced abnormalities on the electroretinogram. CONCLUSIONS/INTERPRETATION: We demonstrate that the inflammatory enzyme iNOS plays an important role in the pathogenesis of vascular lesions characteristic of the early stages of diabetic retinopathy in mice.

[Treatment of infected total knee arthroplasty. When does implant salvage make sense?]. / Therapie infizierter Kniegelenktotalendoprothesen. Wann ist eine prothesenerhaltende Therapie sinnvoll?

Infection of a total knee arthroplasty can be classified as acute, chronic and haematogenic with and without implant loosening. A differentiated treatment concept for all types of infection is necessary. Furthermore, specific treatment has to be initiated early, as any delay is associated with a worsening of the prognosis. Treatment of infection with implant salvage may be one therapeutic option if the implant is not loose. According to the current literature, therapy with retention of the prosthesis may be promising: (1) in the case of early infection (<3 weeks of ongoing symptoms), (2) with unconstrained implants, (3) in the case of infection with a single organism that is susceptible to antibiotic therapy, (4) if soft tissue coverage is not affected, and (5) if the immune system is not compromised. Chronic infections, (semi-)constrained implants and soft tissue defects have to be considered as contraindications and implants should be removed. Early and consequent therapy with operative débridement and specific long-term antibiotic therapy are necessary to achieve implant salvage. The additional application of antibiotics addressing bacterial biofilms have helped to improve the prognosis. Due to the fact that revision arthroplasty is often associated with limited function after infection of the total knee joint, retention of the implant has to be considered a therapeutic alternative in early infection.

[Methods of resolution for haptic assistance during catheterization]. / Lösungsansätze für haptische Assistenz bei Katheterisierungen.

During catheterization navigation within the patient is mainly dependent on a live x-ray image on the screen. Although methods for 3D visualisation and remote navigation of the catheter are discussed and tested still precise positioning is merely the result of intense training and a high skill and level of training of the performing surgeon. This article refers to a system which can be considered as an add-on for existing procedures of catheterization. It compromises of a miniaturised force sensor located at the tip of guide-wires whose prototype is shown here. The measured forces will be presented to the surgeon amplified by an external actuator described in this article. As a result a haptic perception of the forces between the tip of the guide-wire and the vessels walls will be available and enable the surgeon to gain an impression which is comparable to palpation of living vessels from the inside

Interaction between NO and COX pathways in retinal cells exposed to elevated glucose and retina of diabetic rats.

A nonselective inhibitor of cyclooxygenase (COX; high-dose aspirin) and a relatively selective inhibitor of inducible nitric oxide synthase (iNOS; aminoguanidine) have been found to inhibit development of diabetic retinopathy in animals, raising a possibility that NOS and COX play important roles in the development of retinopathy. In this study, the effects of hyperglycemia on retinal nitric oxide (NO) production and the COX-2 pathway, and the interrelationship of the NOS and COX-2 pathways in retina and retinal cells, were investigated using a general inhibitor of NOS [N(G)-nitro-l-arginine methyl ester (l-NAME)], specific inhibitors of iNOS [l-N(6)-(1-iminoethyl)lysine (l-NIL)] and COX-2 (NS-398), and aspirin and aminoguanidine. In vitro studies used a transformed retinal Müller (glial) cell line (rMC-1) and primary bovine retinal endothelial cells (BREC) incubated in 5 and 25 mM glucose with and without these inhibitors, and in vivo studies utilized retinas from experimentally diabetic rats (2 mo) treated or without aminoguanidine or aspirin. Retinal rMC-1 cells cultured in high glucose increased production of NO and prostaglandin E(2) (PGE(2)) and expression of iNOS and COX-2. Inhibition of NO production with l-NAME or l-NIL inhibited all of these abnormalities, as did aminoguanidine and aspirin. In contrast, inhibition of COX-2 with NS-398 blocked PGE(2) production but had no effect on NO or iNOS. In BREC, elevated glucose increased NO and PGE(2) significantly, whereas expression of iNOS and COX-2 was unchanged. Viability of rMC-1 cells or BREC in 25 mM glucose was significantly less than at 5 mM glucose, and this cell death was inhibited by l-NAME or NS-398 in both cell types and also by l-NIL in rMC-1 cells. Retinal homogenates from diabetic animals produced significantly greater than normal amounts of NO and PGE(2) and of iNOS and COX-2. Oral aminoguanidine and aspirin significantly inhibited all of these increases. The in vitro results suggest that the hyperglycemia-induced increase in NO in retinal Müller cells and endothelial cells increases production of cytotoxic prostaglandins via COX-2. iNOS seems to account for the increased production of NO in Müller cells but not in endothelial cells. We postulate that NOS and COX-2 act together to contribute to retinal cell death in diabetes and to the development of diabetic retinopathy and that inhibition of retinopathy by aminoguanidine or aspirin is due at least in part to inhibition of this NO/COX-2 axis.

Hyperglycemia increases mitochondrial superoxide in retina and retinal cells.

Oxidative stress is believed to play a significant role in the development of diabetic retinopathy. In this study, we have investigated the effects of elevated glucose concentration on the production of superoxide anion by retina and retinal cells, the cellular source of the superoxide, the effect of therapies that are known to inhibit diabetic retinopathy on the superoxide production, and the role of the superoxide in cell death in elevated glucose concentration. Superoxide release was measured from retinas collected from streptozotocin-diabetic rats (2 months) treated with or without aminoguanidine, aspirin, or vitamin E, and from transformed retinal Müller cells (rMC-1) and bovine retinal endothelial cells (BREC) incubated in normal (5 mM) and high (25 mM) glucose. Diabetes (retina) or incubation in elevated glucose concentration (rMC-1 and BREC cells) significantly increased superoxide production, primarily from mitochondria, because an inhibitor of mitochondrial electron transport chain complex II normalized superoxide production. Inhibition of reduced nicotinamine adenine dinucleotide phosphate (NADPH) oxidase or nitric oxide synthase had little or no effect on the glucose-induced increase in superoxide. Treatment of diabetic animals with aminoguanidine, aspirin, or vitamin E for 2 months significantly inhibited the diabetes-induced increase in production of superoxide in the retinas. Despite the increased production of superoxide, no increase in protein carbonyls was detected in retinal proteins from animals diabetic for 2-6 months or rMC-1 cells incubated in 25 mM glucose for 5 d unless the activities of calpain or the proteosome were inhibited. Addition of copper/zinc-containing superoxide dismutase to the media of rMC-1 and BREC cells inhibited the apoptotic death caused by elevated glucose. Diabetes-like glucose concentration increases superoxide production in retinal cells, and the superoxide contributes to impaired viability and increased cell death under those circumstances. Three therapies that inhibit the development of diabetic retinopathy all inhibit superoxide production, raising a possibility that these therapies inhibit retinopathy in part by inhibiting a hyperglycemia-induced increase in superoxide production.

Non-uniform distribution of lesions and biochemical abnormalities within the retina of diabetic humans.

OBJECTIVE: Microaneurysms, acellular capillaries, pericyte ghosts, and thickening of retinal capillary basement membrane are characteristic of diabetic retinopathy, and are believed to be sequelae of excessive blood glucose. Previous studies by us in dogs demonstrated that lesions of diabetic retinopathy were not uniformly distributed across the retina, but were significantly more numerous in the superior/temporal areas of the retina. In the present study, the distribution of these lesions and the biochemical abnormalities postulated to play a role in their pathogenesis have been evaluated in retinas collected at autopsy from diabetic patients. METHODS: Retinas were divided into quadrants (nasal, temporal, superior, inferior), the vasculature exposed by the trypsin-digest method, and the frequency of the lesions compared among the quadrants. Homogenates taken from the mid-retina of nasal and temporal quadrants of retina were used to explore regional differences in expression of Glut1, PKCbeta, and iNOS (Western blots) and caspases (enzymatic activity). RESULTS: Microaneurysms, acellular capillaries and pericyte ghosts were not uniformly distributed across the retina, and were significantly more numerous in the temporal retina than in the nasal retina (P < 0.05). In contrast, the thickness of retinal capillary basement membrane was not found to differ significantly across the retina. In our limited study, activity of the pro-inflammatory protease, caspase 1, was the only biochemical abnormality where there was both a significant diabetes-induced alteration in activity and also a significant difference between retinal quadrants. Expression of the glucose transporter, Glut1, was significanlty decreased in diabetes, but there was no significant difference in expression between the quadrants. Expression of iNOS was increased only in temporal retina in diabetes (but no significant difference between quadrants), and PKCbeta tended to be greater than normal in both temporal and nasal retina. CONCLUSIONS: Retinal microvascular disease does not develop uniformly across the retina of diabetic patients, even though the different regions are exposed to the same level of hyperglycemia.